Can You See the Fire Beacon?

Before mobile phones, radio and even the telegraph, fire beacons were used as an early warning system designed to alert communities to the approach of hostile forces. The beacons were deliberately positioned on prominent high ground, allowing one fire to be seen from another. When an enemy was spotted, a chain of burning beacons could then relay the warning across the landscape.

The system was particularly important during the threat of invasion by the Spanish Armada in 1588. Beacons could take various forms, from simple bonfires to barrels of pitch or iron fire baskets mounted on tall wooden poles. Some were substantial enough to have permanent structures.

My Hampshire Fire Beacons map explores how this historic warning network might have worked. It plots known and suspected beacon locations across Hampshire and allows you to investigate which sites could potentially have been visible to one another. It also uses elevation data to allow you to search for possible locations for any fire beacons lost from the historical records.

Select a beacon and the map can calculate its lines of sight to all the other beacon locations. The analysis uses elevation data to establish whether the intervening terrain would have blocked the view. Visible connections are drawn in green, while obstructed routes are shown in red. You can also adjust the assumed height of the beacon above the ground to see how this changes the network.

There is another feature which makes the map particularly interesting. You can ask it to search the surrounding landscape for prominent hilltops which might have made suitable locations for additional beacons. These hypothetical sites are added to the map so that their potential lines of sight can be tested against the existing network.

The historical data comes primarily from Old Hampshire Mapped, which has painstakingly examined a succession of historic maps to identify possible beacon sites. These include maps by Christopher Saxton, John Norden, Wenceslaus Hollar, Joan Blaeu and others, dating from the late sixteenth century onwards. The website compares the symbols and place names used by different mapmakers and provides approximate locations for many of the sites.

There are, however, some significant problems with the accuracy of this data. Historic mapmakers did not all use the same symbols to represent beacons. Some show posts or flames on hilltops, others use different illustrations, while some simply label a place as a beacon. A symbol might be ambiguous, a location only approximately identifiable, or a name might have survived long after the original beacon had disappeared. Even Old Hampshire Mapped cautions that the absence of a beacon from a particular map is not evidence that one did not exist.

The locations plotted on my map should therefore be treated as historical leads rather than as a definitive inventory of beacon sites. The line-of-sight calculations are also approximations. They depend on the accuracy of the location data, the elevation model and the assumed height of each beacon. A green line does not prove that two historical beacons could communicate in practice, any more than a red line proves that they could not: vegetation, buildings, weather and the precise construction of the beacon could all have made a difference.

Nevertheless, I think the process is useful as a way of investigating the historic network. I think it shows that there are very few visible connections in the 'known' network. This might suggest that other beacons existed which have not yet been identified. The map's hypothetical hilltop locations provide possible candidates for further research. They are not discoveries in themselves, but places worth investigating in historic maps, documents, local histories and archaeological records.

In other words, my map does not claim to rediscover Hampshire's lost fire beacons. However it might suggest a possible method for searching for fire beacons 'lost' from the record.